title: Enantioselective nucleophilic difluoromethylation of aromatic aldehydes with Me3SiCF2SO2Ph and PhSO2CF2H reagents catalyzed by chiral quaternary ammonium salts.
abstract: BACKGROUND
  Although the nucleophilic difluoromethylation of aldehydes, ketones, and imines has been realized with PhSO(2)CF(2)H and related reagents, there are still no reports on the enantioselective nucleophilic reactions.
  
  
  RESULTS
  With a chiral quaternary ammonium salt as the catalyst and KOH as the base, we describe the first enantioselective difluoromethylation of aromatic aldehydes with PhSO(2)CF(2)H or Me(3)SiCF(2)SO(2)Ph. The enantioselectivity is substrate-dependent and for 2-chlorinated benzaldehyde an ee up to 64% was obtained.
  
  
  CONCLUSIONS
  These results provide some insights into the enantioselective nucleophilic difluoromethylation chemistry, which will stimulate further progress in this field.
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, China.
authors.forename: Chuanfa
authors.initials: C
authors.lastname: Ni
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Jinbo
authors.initials: J
authors.lastname: Hu